Steam-engine.



IVI. A. GREEN.

STEAM ENGINE.

APPLICATION FILED JAN.20|19I5. Y I

Patented Nov. 9, 1910.

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A TTOHNEYS M. AJGREEN.

STEAM ENGINE.

APPLICATION FILED 1AN.20, i915.

Patented Nov. 9, 1915 3 SHEETS-SHEET 2.

A TTOR/VE V8 M. A. GREEN.

. STEAM ENGINE.

APPLICATION FILED 1AN.20.1915.

Patented Nov. 9, 1915.

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A TTOHNEYS MARTIN A. GREEN, OF`PHILADELPHIA., PENNSYLVANIA.

STEAM-ENGINE.

l Specification of Letters Patent.

Patented N ov., 9, 1915.

Application filed January 20, 1915. Serial N o. 3,261.

To all whom t may concern.'

Be it known that 1, MARTIN A. GREEN, a citizen of the United States, and a resident of Philadelphia, in the county of Philadelphia, and State of Pennsylvania, have invented a new and useful Improvement in Steam-Engines, of which lthe following is a specification.

Hy invention is an improvement in steam engines of the type known as center discharge or uni-directional iow steam engines, that is, that type of engine in which the steam enters at the ends of the cylinder through admission valves and follows the piston practically the entire length of the stroke and exhausts through a center exhaust port which surrounds the entire periphery of the cylinder. rThe steam in such engines once it enters the cylinder, never returns on its path within the cylinder and hence the name, uni-flow steam engines.

The object of this improvement is to provide improved means which is controlled automaticallyv by the steam without the aid of mechanism connecting to the moving parts of the engine to control and produce the proper compression when the engine is running non-condensing and condensing.

1n the drawings Figure l is a longitudinal vertical section through the cylinder of an engine constructed in accordance with the invention,-F` ig. 2 is an enlarged longitudinalsection of the piston, Fig. 3 is a bottom plan view of the piston, Fig. 4 is a section on the line 4 4 of Fig. 2, looking in the direction of the arrows adjacentto the line, and Fig. 5 is an end view of the piston.

As is known with an engine `of the character in question running non-condensing (9.5% of the steam engines in use so running) 18 to 20% clearance is necessary to provide for the volume ofsteam remaining in the cylinder at the end of each stroke, and which must obviously be compressed by the return stroke of the piston. The object of the present invention is to provide for the exhaust and removal of this steam from the cylinder, and this is brought about by means cf-a double headed auxiliary valve in the piston, and operating in conjunction with a storage chamber also in the piston, the chamber having a port at each end of the piston, and the valves coperating with the ports to alternately open and close the ports,

.prises a cylinder consisting of a cylindrical 'body 1, closed at its vends by heads 2 and 3,

and admission ports 4 and .5 are arranged 'at the ends of the cylinder for admitting the steam thereto. The steam is admitted to a chamber, formed adjacent to the cylinder and extending longitudinally thereof through a port 6a, and the chamber is adapted to connect at each end with the ports 4 and Valve seats 7 and 8 are formed at the ends of the chamber between the chamber and the ports 4 and 5, and valves 9 are provided for eoperating with the seats.

Each valve has secured thereto a stem 10, the valve being connected to the steirr near its lower end, and each stem engages at its lower end an opening in a nipple 11 on the cylinder coaxial with the adjacent seat. On the opposite side of the valve from the nipple each stem 10 passes through a guide sleeve l2 held in a guide 13, supported above the seat, each of the guides 12 being approximately cylindrical, and having an annular groove l'or receiving a packing ring 14 to assist 1n preventing the escape of the motive fluid through the guide around the sleeve. The lower end of each sleeve has a frustoconical head as shown, and an annular rib or shoulder is formed between the head and the body of the sleeve, each shoulder engaging a similar shoulder in the guide, to limit the upward movement of the sleeve.

A wheel or roller support 14 is connected with the outer end of each stem, and a wheel or roller 15 is journaled on each support. Each of the rollers 15 is above the valve operating stem 1G, and the stem is provided with enlargements 17 and 18, for engaging between the roller 15 and a roller lavjournaled on the guide on the opposite side of the stem from the adjacent roller 15. A coil spring 19 normally presses each roller support toward the cylinder,'acting to hold the valve closed, and the tension of each spring may be regulated by means of adjusting mechanismv 20, cooperating with the outer end of the guide. The valve operating mechanism forms no part of the present invention, and for this reason is not more closely described. The stem 16 is connected to one end of a lever 21, pivoted interme- .I diate its ends to 'a support 22 and operated by the piston in any usual or desired man- Iier.

,iAt its center a. portion of the cylinder is offset outwardly to form an annular chamber 23 at the center of the cylinder, and extendingv entirely around the same, and opening into an exhaust chamber 24 below the cylinder. `From this chamber-24 the steam may pass tothe atmosphere in any desired or suitable manner. The piston 24 is hollow or chambered as shown more particularly in Figs. 1 and 2, and at the center of the heads 25 and 26 of the piston hubs are provided, the hub 27 of the head 25 be# .ing counterbored at-the outer face vof the i :cylinder as indicated at 28. The hub 29 ,of

the head 26 is internally threaded, and the piston rod 30 is reduced at the point where it enters the piston through the head 26,"

the said head being that adjacent to the cross head. l

At the junction of the reduced portion with the main portion of the piston rod, the 'rod is externallythreaded as shown at 31,

,to engage the internally threaded hub 29,

and at the hub 27 the rodis again reducedl as shown at 32 to engage the said hub. The end of the piston rod is externally threaded as shown at .33, this threaded portion extending into the counterbore. 28, and a nut 34 is threaded on to the threaded portion 33 within the counterbore. .The head 26 bears against the annular shoulder formed between thev reduced portion and the body of the piston `rod,jand the annular shoulder formed at the inner end of the reduced portion 32 bears against the inner 'face of the head 25. The piston is thus locked from movement with respect tothe piston rod in either direction.

At its lowesty portion a chamber 35 is formed in the piston, the said chamber having no communication with the interior of the piston, being separated therefrom by a web 36, and bearings 37 are formed at the junction of the web with the heads, the said bearings Abeing in alinement as shown. The

bearings are at the inner sides of radial extensions 38 from the chamber 35, and at the outer side of each extension a port 39 is provided, the said .ports being circular* and coaxial with the I bearingsl 37. The outer end of eachl port is beveled or flared as shown at 40, to form a valve seat,vand a -frusto-conical valve 41 coperates with each seat. The valves 41 have hubs 42 on their A'eo inner faces, the said hubs being internally threaded and being engaged by threaded.

portions at the end of a stem 43.

annular grooves 44, and the periphery thereof is also provided with one or more grooves 45. v'Ihevalve stem 43-is of such length that the valves cannot both seat at the same time.

lVhen one valve is seated, the other valve is unseated, and the movement'of the stem is limited in either direction by the engagement of the valves with their seats.-

The Aports 39 are` for placing the chamber 35 in communication with the interior ofthe I cylinder, and at the chamber the wallof'the Jolpiston is provided with a number of open-A The portst-l are arranged intermediate 'l the ends of e piston, and betweenA the side walls of the chamberv 35 formed by the web 36. Onv the outer'side of each of the side walls Aabove mentioned, openings or ports 47 are provided for permitting the interior of the piston todrain. vThe piston has water grooves 48 at each end, and when the valves 41 are closed, their outer faces'will be iush with the outer faces of the heads of the piston.

It will be noted 'from an inspection of Fig. 1 that the relative dimensions oi?` the piston and cylinder are such that the entire."

length of the piston may be received in those portions of the cylinder on opposite sides of the annular recess or chamber 23. That is, at the end of the ystroke'of the pistonv away from the cross head, the outer surface of the head 26 is flush with one wall 'of thechamber 23, while at the end of .the stroke of the piston toward the. cross. head the outer surface of the head 25 is .lush with 'the other wall of the said chamber. i

The operation of the improved engine-v is as follows z-When the valve 9 at the port 7 is opened to permit the motive fluid to iow from the chambery-6 by 'way of the portl 4 to the outer end .of the cylinder, the pis# ton will be driven toward the crossv head. When the piston starts toward the cross head, the parts occupy the position shown yin Figs. land 2, that is, the valve 41 at the outer end' of the cylinder is closed, and the valve 41 ade'` jacent to the chamber 23 is open. Whenv now the piston starts towar'cl'the cross head,

as soon as it covers the` annularp'assage `between the cylinder and the chamber 23, the

exhaust to the atmosphere is'closed. and any steam remainingl i-n the inner endl of the cylinder would necessarily be compressed i were there no outlet for the same. However the valve 41 at the inner endV of the piston is open and .any exhaust steamthat may remain in the inner end of the cylinder passes through the port 39 -into the/,chamber 35. I v

As the openings-or ports 46 pass over the central exhaust suchexhaust steam' asmay be in the chamber 35, will pass out into the-` exhaust chamber 24. It will be noted that the openings 46 leading fiom the chamber 35 of the piston do not extend to the ends of the piston, the openings stopping at a distance of from two to three inches from the ends. This is for the purpose of permitting the reservoir or auxiliary chamber 35 in the piston to be cut od from the center exhaust before the piston reaches the end of its stroke, so that pressure will be created in the chamber 35 sufficient to shift the valve stem and the valves before the piston reaches the end of its stroke in either direction. As soon as the chamber 35 is cut olf from the exhaust, pressure begins to generate in the chamber, and the cutoff is so set that there will be suiicient pressure'in the chamber 35 to shift the valves to close that in advance and open that in rear, and to prevent any contact of the valves with the cylinder, when cooperating with the pressure in front of the piston and in front of the advance valve.

Even when the engine is shut down and steam turned off and the engine is running of its own momentum neither valve'willl touch the cylinder heads. Before the stem 13 is moved however, the central exhaust is opened by the piston uncovering at least a portion of the same, and when the valve stem is moved to .seat the valve at the inner end of the piston the central exhaust is fully opened. lVhen the piston moves outward the valve 41 at the outer end of the piston will be opened so that any exhaust steam that may be trapped in the youter end of the cylinder may pass into the chamber 35 and out through the openings 4G into the exhaust chamber. Thus that steam slight-ly above atmospheric pressure that does not exhaust is provided for, passing .into the chamber 35, and no clearance is necessary at the ends of the cylinder.

The operation is entirely automatic, no attention being required, nor is there any complicated mechanisms to get out of order, neither' is there springs to break or to become rusted. At the end of the stroke of the piston in each direction a large exhaust passage is op'ened, suliicient to care for practically all of the steam. That steam which does not have sufficient pressure to cause it to exhaust will pass out by wav of the chamber 35 and the openings 46. These openings 40 are open until just before the end of the stroke of the piston, that is, until just before `the moment when the valve stem 43' is shifted.

Any excess of steam that may not be able to pass out through the openings 46, will be cared for in the chamber The grooves del and 45 of the valves 41 are compression grooves to permit the formation of air or steam cushions to make the valves seat noiselessly and to eliminate noise.

The openings 4G do not, as before stated, extend to the endsof the piston, the series terminating a sutlcient distance from the end, so that the communication between the chamber 35 and the exhaust chamber 24 will be cut off just before the piston reaches the end of its stroke in each direction. Thus the end of the cylinder1 toward which the piston is moving will hold suliicient steam to provide a compression su'lticient together with that in the chamber 35, to shift the valve mechanism, that is, to close the valve adjacent to the endI toward which the piston is traveling. At this same moment' the piston uncovers the central exhaust, thus relieving the pressure on the valve that would otherwise resist the shifting of the valve mechanism.

Preferably the wall of the piston at the chamber 35 is perforated between the packing ring 1S at each end, .and sundry of the openings at the ends may be closed by plugs as indicated at 49. By means of these plugs the exact amount of compression necessary may be provided. Hence in the construction the piston serves not onlv as an exhaust valve but in addition serves for what may be practically termed a sliding valve, thecolnpression being increased or diminished by the plugs 4S. The engine can for this reason be run with a minimum of clearance and without back pressure. so `|hat the full compression of the steam ..ay be utilized, and practically the same resul* may be attained with an engine running non-condensing as though the engine were run condensing.

It will be seen that in carrying out the invention no additional ports are necessary,

nor is there any change in the external appearance of the engine, the valve mechanism being self-contained within the piston. A feature of importance is,V that were the engine built and set to run non-condensing, in order to provide for its running` condensing, it lis only necessary to unscrew one of the auxiliary valves 41, remove the washers shown at 50 in Fig. 2, and return the valve to place, turning the valve to take the place of the washer removed, and space the valves in such manner that they will both be seated,thus closingl the 'auxiliary ports. These washers are of an aggregate thickness corresponding 'tothe length over all of the valve stems and valves, over that of the piston, and when the washers are removed, and the valve heads 1l turned inwardly to the extent of their' movement the valves 41 will tit closely to their seats at each end of the piston, and the engine is in Shape to run condensing. That is, by'removing the washers as above described the piston is made a closed piston without openings at either end..

tom of the cylinder, While atthe same time it makes a perfect system of lubrication in the bottom of the cylinder where the Wear nular rexhaustpassage nat each end/qi its stroke, said piston having at the ,under side thereof a chamber and a series' of radial openings leading from the chai/uber vfor registering with the exhaust passage as. the piston moves thereover, said/piston having a port at each end of the chainber,ffor

guided movement in the piston, a valve con` nected with each end of the stem, said stem being of greater length than the piston to prevent the simultaneous closing of the valves, the radial openings of the chamber in the piston being spaced from the ends of the piston to cut off the auxiliary chamber from the exhaust before the piston reaches the end of its stroke to provide sufficient pressure within tbe chamber and lin front of the piston to shift the valves, each valve having annular grooves on its periphery and on its outer face. i 2. In a reciprocating steam engine, the combination with the cylinder having inlet ports at its ends, and provided at its center with an annular exhaust chamber communicating with. the cylinder throughout its extent, a piston withinl the cylinder, and. of a length to uncover the exhaust passage at each eiid of its stroke, said piston having at the under side thereof la chamber and a series of openings leading from the chamber for registering with the exhaust passage, said piston having a port at each end thereF of (,:oiiiuiunicating with the chamber, a valve for cooperating with each port, a stem connecting the valve and of greater length than the piston to prevent the simultaneous seating of the valves, sai-il piston having means for guiding the stem to constrain it to move parallel with the axis of the piston.

3. In a reciprocating steam engine, the

combination With the cylinder having inlet ports at its ends, and provided at its center with an annular exhaust chamber commuA nicating lwith the cylinder throughout itsy extent. a piston Within the cylinder, and of l a length to uncover the exhaust passage at each end of its stroke, said piston having at the under side thereof a lchamber and a series of'openings leading from the chamber for registering.: with the?,Lzexhaustpassage,`

said piston having afportat each end tliereof communicating With the chamber, a valve stemimounted to move longitudinally of the. piston and parallel With theaxis thereof and of greater length than the piston, and a valve secured to each end ofthe stem for closing the adjacent port When'the stem is moved away from the port, each valve lbeing adapted to be moved yinto closed position by the pressure in advance of the piston when the piston nears the end of its stroke in that direction. l

4. In a reciprocating steam engine, the

Lcombination with the cylinderv having inlet ports at its ends and having a central' exhaust port, a piston iyithin the cylinder and of a length to uncover the exhaust port at each end of its stroke, said piston having a chamber extending longitudinally thereof and having a port at each end of the piston,

the piston having openings leading fromtlie chamber and'adapted to register with theexhaust port, a valve for each port, and a stem connecting the valves and of greater length than the piston to prevent the simultaneous closing of the valves, the radial openings of the chamber in the vpiston being spaced from the ends of the piston to cut off the auxiliary chamber from the exhaust before the piston reaches the end of its stroke to provide sufficient pressure Within the chamber and in front of the piston to shift the valves. I

In a reciprocating steam engine, the combination with the cylinder having inlet ports at its ends and havinga central exhaust port, a piston in the cylinder and having a chamber extending longitudinally thereof and having a port at each end of the piston, the piston having openings for placing the chamber in communication with the exhaust, a valvecoperating `with each port for closing the same, and a rigid connection between the valves of greater length than the piston to prevent the simultaneous seating of the valves, ,the radial openings of the chamber in the piston being spaced from.

ports at its ends, and the piston in thecylinder, the piston having a chamber and having a port for the chamber at each end of the piston, a valve coperating with each port, a rigid connection between the valves and of greater length than the piston topreventthe simultaneous seating of the '\.1'alve,l 'I said cylinder having a central exhaust 'an-dthe .piston @having openings leadin' rom I i-theehambergandadapted to regista with/fsb i ports at its ends and a central exhaust, of a combined piston and exhaust valve, said piston being chambered and having-ports lead- Y ing from the chamber to the ends of the pis- 5 ton. and having' ports adapted to communicate With the .exhaust of the cylinder as the piston moves thereover, and arranged to cut off the eh amber Vfrom the exhaust before the piston reaches the end of its stroke in either l0 direction to provide for a degree of compression in front of the piston, valves Coperat-` ing With the ports at the ends of the piston,

and a rigid connection between the valves and having guided movement in the piston and of a length to prevent the simultaneous closing of the valve, said Valves opening out- Ward from the piston and being adapted to be opened and closed by the pressure in front of the piston.

MARTIN A. GREEN.

Witnesses l CHARLES F. WIGGINS, LEON B. TANTIM.- 

